Prognostic factors and therapeutic options for relapsed or refractory acute myeloid leukemia

Considerable progress has been made in the treatment of acute myeloid leukemia (AML); however, current therapeutic results are still unsatisfactory in untreated patients and poorer in those with primary refractory or relapsed disease. The biological and clinical characteristics of relapsed AML are analyzed here.

Most relevant literature in English language on relapsed AML from 1990 to 2004 was considered paying particular attention to the heterogeneity of the disease and prognostic factors at the time of relapse; therapeutic results in terms of second complete remission (CR) with conventional chemotherapy, stem cell transplantation and new agents are also summarized.

Molecular relapse is a current indication for treatment of acute promyelocytic leukemia (APL); however, data are emerging for the treatment of molecular relapse in AML other than APL, such as AML with t(8;21) and AML with inv(16). Age, duration of first remission and cytogenetics are the most relevant prognostic factors in relapsed AML. Promising therapeutic results have been reported for the antiCD33 monoclonal antibody conjugated with calicheamicin and the new nucleoside analog clofarabine; preliminary studies indicate that FLT3, farnesyl-transferase and bcl-2 inhibitors are active in relapsed AML.

All relapsed elderly patients and young adults with CR1 lasting for less than 12 months are ideal candidates for experimental therapies. Efficiently conducted phase II randomized trials are needed in order to achieve relevant information to be translated into phase III trials.